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Date:   Thu, 20 Jun 2019 12:51:24 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Christoph Hellwig <hch@lst.de>,
        Potnuri Bharat Teja <bharat@chelsio.com>,
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Subject: Re: use exact allocation for dma coherent memory
Message-ID: <20190620105124.GA25233@lst.de>
References: <20190614134726.3827-1-hch@lst.de> <20190617082148.GF28859@kadam> <20190617083342.GA7883@lst.de> <20190619162903.GF9360@ziepe.ca>
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On Wed, Jun 19, 2019 at 01:29:03PM -0300, Jason Gunthorpe wrote:
> > Yes.  This will blow up badly on many platforms, as sq->queue
> > might be vmapped, ioremapped, come from a pool without page backing.
> 
> Gah, this addr gets fed into io_remap_pfn_range/remap_pfn_range too..
> 
> Potnuri, you should fix this.. 
> 
> You probably need to use dma_mmap_from_dev_coherent() in the mmap ?

The function to use is dma_mmap_coherent, dma_mmap_from_dev_coherent is
just an internal helper.

That beiŋ said the drivers/infiniband code has a lot of
*remap_pfn_range, and a lot of them look like they might be for
DMA memory.